Extraction of an insecticidal protein fraction from the parasitic fungus Conidiobolus coronatus [Entomophthorales]

From our experiments it appears that parasitic fungus, Conidiobolus coronatus, infected 12 insect species we have tested, while another 8 species did not suffer after contact with this pathogen. The culture filtrates and mycelial homogenates of C. coronatus contain toxic proteins. By means of two steps FPLC: gel filtration followed by ion-exchange chromatography, we isolated a 30 kDa toxic protein from the culture filtrate. The 30 kDa protein appeared to be very potent on Galleria mellonella larvae: LD₅₀ was less than 5 ng/larva. Rabbit polyclonal anti-30 kDa immunoglobulins specifically recognized this fungal toxin. Using antibodies we showed that 30 kDa mycotoxin is present in C. coronatus conidia, hyphae and is released by the fungus into the incubation liquid medium.